1. Field of the Invention
This invention is related to a yarn winding device in which a yarn produced by a spinning machine, a false twisting machine, a rewinding machine or the like is wound in the form of a square cheese, a biconical cheese, a cone or the like.
2. Description of the Related Art
Generally speaking, in methods of producing a yarn by using, for example, so called innovated spinning machines such as an open end spinning machine, an air spinning machine or the like, or a false twisting machine and a draw-texturing machine or the like, the yarn produced or treated in such a yarn forming or a yarn processing device thereof is delivered therefrom by a delivery roller at a predetermined yarn speed and fed to a yarn winding means, and thereafter, wound on a bobbin by a yarn winding means as a package, i.e., a so-called square cheese, biconical cheese, cone or the like.
The above mentioned yarn winding means usually consists of a guide provided at a traversing point for guiding a yarn to a predetermined position, a roller having a groove on a surface thereof and rotated at a predetermined revolving speed by a driving means, and a cradle for rotatably supporting a bobbin and swingably mounted on an axis provided on a frame of a machine. The yarn delivered from a yarn processing portion is wound up onto a bobbin rotated by a contact friction driving method with a roller having a groove by which the yarn is traversed.
On the other hand, a yarn may be traversed by a traversing guide connected to a rotary scrolling cam, whereby the yarn is traversed in a direction parallel to a surface of a bobbin. When a yarn is wound onto a bobbin to form a package, such as a square cheese, a biconical cheese, or the like, by the yarn winding means mentioned above, a problem arises in that, during the yarn traversing, a yarn tension in a yarn winding process will become relatively high when reaching one end of a traversing range, but this tension will become relatively low when moving back to the center of the traversing range, because of a difference in the yarn length from a guide for a traversing point to an end portion of the range and the length of the yarn from a guide for a traversing point to a center point of the traversing range thereof.
Therefore, an edge projection on both ends of a package is often caused by an accumulation of yarn on the edge thereof or an edge collapse on a surface of a package caused by a relatively high hardness of a wound bobbin occurs.
Also a problem arises in that a difference of a hardness on a bobbin will occur at the end of a package and at the center portion of the package.
This problem will frequently arise in the case of a yarn wound on a bobbin by a soft winding method.
On the other hand, when a yarn is wound onto a package in the form of a conical cheese, a cradle provided with a mechanism to hold a bobbin at a certain inclination against a driving roller having a cylindrical shape is used to give one end of the package a relatively large diameter and the other end thereof a relatively small diameter, as an increment of a package diameter wound thereon. But during a yarn winding operation of this method, the yarn winding tension will greatly vary between an one end portion of a package having a large diameter and the other end portion thereof having a small diameter, and a contact pressure between a package and a driving roller also will be varied because of, for example, yarn accumulation, difference in hardness of a package at both ends thereof, and a cradle setting error, therefore the package is not more often driven at the center portion of a driving roller than at one end portion of the package having a large diameter or at the other end portion having a small diameter
Accordingly, when a package is driven on one end portion thereof having a large diameter yarn breakage will occur because the yarn winding speed is decreased, resulting in an increase of slack portions thereof and errors in the control of a yarn pass. On the other hand, when a package is driven on the other end portion thereof having a small diameter, yarn breakage will also occur because the yarn winding speed is increased resulting in a increase of the yarn winding tension.
As can be seen from the above description, the problems of yarn breakage, an edge projection on both ends of a package, and an edge collapse on a surface of a package are caused by variations in the tension, which occurs because of the difference in the winding diameter and variations of a driving point. Therefore, a method in which an absorbing means for mechanically absorbing a variation of a yarn speed, such as a tension compensator, is used to reduce the variations in yarn tension has been disclosed.
A typical absorbing means for mechanically absorbing variations of a yarn speed is disclosed in Japanese Examined Patent Publication No. 61-19541, but even by using such an absorbing means, the above problems still exist, in that a simultaneous compensation of a yarn tension can not be implemented when there is a variation in a yarn tension, because a cycle of a variation of a yarn tension is shortened when a yarn winding speed exceeds 200 m/min, and thus interferes with an inherent vibration of the absorbing means, finally, the yarn winding operation can not be continued.
Further, when using a cone cheese as a package, if a tapered angle thereof exceeds 2.degree., variations of a yarn tension will become large and a cycle of a variation of a yarn tension will be shortened, and therefore, a compensation of a yarn tension can not be carried out for the same reason as mentioned above; therefore, it has been a problem to use such a system in actual practice
The object of the invention is to provide an apparatus for winding a yarn onto a package such as a square cheese, biconical cheese or cone cheese having a tapered angle of at least 2.degree., in a winding configuration comprising a soft winding or a hard winding to provide a package having a uniform hardness and a uniform shape.